


who’s the baby now?

by Star_less



Category: Spider-Man: Homecoming (2017), The Avengers (Marvel Movies)
Genre: Age Regression/De-Aging, Complete, De-Aged Tony Stark, Fluff, Fluff and Humor, Gen, Humour, Inspired by Fanart, One Shot, Peter’s a good babysitter, Post-Avengers (2012), Slice of Life, Superfamily (Marvel), Teen Peter Parker, Tony Stark Needs a Hug, Tony has a baby side and a grown up side, and is trying to balance both, if u want something silly and light, this is OPs pure self indulgence fic, this is it, tony really needs to learn to be more careful in the lab
Language: English
Status: Completed
Published: 2019-05-21
Updated: 2019-05-21
Packaged: 2020-03-09 02:05:49
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 3,430
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18907300
Author URL: https://archiveofourown.org/users/Star_less/pseuds/Star_less
Summary: after an accident in the laboratory, Tony Stark finds himself aged down to roughly a year old. Which wouldn’t be so bad, except he quickly discovers that his brain hasn’t entirely been taken over by a drooling colourful mush and shards of his grown up conscience leak through. Which makes it all the more boggling when Pepper invites Peter over, ‘to babysit’.”Mr. Stark’s ababy!” Peter squeaked, mouth gaping. At the sound of his protege’s voice, Tony dived over to the door of the playpen.What the hell was Pepper playing at?!





	who’s the baby now?

**Author's Note:**

> this is. pure, pure self indulgence. some sort of cracky, fluffy mashup. A friend of mine made some fanart, and I saw it and was like, huh. I smell a fic. So here it is. I wrote this under the pressure of university exams (in eight days. EIGHT DAYS) and while having a panic attack over a Cyberman. Long story. Actually no it’s not; I don’t like them.
> 
> not beta read; too busy to sort it. Soz!

“Peter? Peter, sweetheart. It’s Pepper.”

”Mhhhm,” Peter whispered, frowning at the blurry image of Miss Potts on his phone screen. Yeah, he could see that. Not that he minded - but it was lunchtime, and today wasn’t a ‘Miss Potts’ sort of day. Today wasn’t even a ‘Happy’ sort of day. No; today was a ‘Mr. Stark’ day and that meant Mr. Stark would pick him up from school in the Audi and take him back to the Tower. Peter liked Mr. Stark days best because Mr. Stark always took him for a Krispy Kreme, or a McDonalds, or a sneaky icecream sundae before he went to the Tower and it... well, it was nice to have that time when it was just them together. It was... kinda special. Fun, too. Not that Miss Potts days or Happy days _weren’t_ fun, they were just... different. 

(And Peter secretly relished the shocked look on Flash Thompson’s face as the Audi sped off with Peter grinning out of the window.)

But if Miss Potts was calling him, something must have gone wrong. Something must have happened and now it was a Miss Potts sort of day after all. Peter swallowed thickly, trying to bat away the wisps of anxiety welling in his tummy. “What’s up?”

”Tony’s had...” Pepper was looking at Peter but she was also sort of looking away in the distance. Slowly her eyes widened. “Tony, no!” She wailed. 

At that point she must’ve thrown her phone down as Peter got a view of the overhead lights in Tony’s laboratory and DUM-E chirruping into view. Peter giggled softly; Pepper batted the burbling robot away and returned to view. In the background, Peter was sure he could hear faint crying. He frowned again. Since when did Mr. Stark and Miss Potts have a baby?

Pepper was breathless. “Tony’s had a little bit of an, uh...” she looked off to the side again. “... _accident_. I need your help, sweetheart. Please? I’ll pick you up from school. Now. I’ve cleared it with the Head, don’t worry. You’ll be done by six.” _She hoped_. “Bruce will help you.”

*

Peter had said yes, but quite what he was throwing himself into he had no idea. Miss Potts had remained annoyingly tight lipped about the whole situation the entire ride home; apart from a brief moment where she calmed him and promised that no, Mr. Stark had not been in a car accident, and was perfectly unharmed. But that left Peter stumped. What other accident could there possibly be? Miss Potts had said he would only understand once he saw Mr. Stark for himself, but what sort of answer was that?!

”Miss Potts... I- I don’t get it, is Mr. Stark really okay?” Peter asked, watching Pepper’s heels click toward Tony’s lab. 

“See for yourself, kiddo.” Pepper laughed softly, pushing open the door.

Like Miss Potts had said, the lab looked fine. Bruce Banner was stood in the corner frowning over some brightly coloured vials of chemicals. The robots were shuffling along without a care in the world.

And there was a baby sat in the middle of the room, loosely encased by a pastel-coloured foam playpen. The baby was sat on its bottom, and actually looked quite immersed in the book he was reading. A closer look at it told Peter it was a physics textbook. Huh. Not quite, ‘Each Peach Pear Plum’, then.  
An even closer look at the baby told Peter that it - he - was wearing a suit. It was miles too big for him, dragged off of his arms and dangled off of his ankles (and where the trousers had slid off Peter could easily see a diaper so, hey, at least the suit wouldn’t be ruined) but was nothing compared to the glasses, which were so close to tumbling off of his face they may as well have not been there in the first place. Which could only mean...

”Mr. Stark’s a _baby_!” Peter squeaked, mouth gaping. At the sound of his protege’s voice, Tony lost track of where he was ‘reading’ (don’t tell Pepper, but the words were starting to make much less sense than usual) and dived over to the door of the playpen, ineffectively pulling at the foam pipes to be freed. _What the hell was Pepper playing at, inviting the kid over? As if this wasn’t humiliating enough already. Bruce has already had the pleasure of seeing him piss himself and be wrestled into a diaper by Pepper but this — this was something else._   
_“Uh, Pep.”_ He said, pointing at the kid and throwing a glare toward his fiancée. “ _No dice. Nuh uh. Kid goes home. Now._ ”  
Unfortunately, his vocal chords hadn’t developed the ability to speak in the last sixty minutes; all that came out of his mouth was a series of wet coos and gurgles with a couple of headshakes for emphasis — and Pepper melted on the spot. Usually Tony would have milked this for all he was worth but it was much less fun when he was getting treated like a one year old.   
“Peter’s here to help you, sweetheart.” Pepper said, scooping Tony up from the playpen and squeezing him. “He’s gonna work with Bruce and get you all fixed.”  
She gestured to the chemicals Bruce was mixing together. “Since you’re too little to do this by yourself.”  
Geez. Did he really need a reminder? Whining softly, Tony laid against Pepper and instinctively stuck his fingers into his mouth, happily covering them in drool. He had only been a baby for a short while, but this felt pretty comforting, so he watched Peter and Bruce working while Pepper swayed and slowly she swayed him off to sleep.

With Tony asleep and therefore not so much of a cool distraction, Peter got his head down and worked alongside Bruce for a solid two hours. Pepper and Tony had left by then, and the only noises that reminded Peter that baby Tony even existed were some unhappy gurgles and Pepper’s voice floating softly over them. ‘Are you hungry, baby?’ She asked. The gurgles seemed to increase in volume and got considerably more unhappy; Pepper persisted. ‘No, not that baby food. I promise. I’ll get you a grilled cheese. Some soup?’  
Hearing this from the laboratory, Peter gasped. His tummy also began to rumble at the prospect of food. “Mr. Stark’s awake!” he shook Bruce’s arm excitedly. “Can I go see him?”

Bruce looked at the work they had done. They had made a considerable dent in identifying the chemicals Tony had used to turn himself into a baby in the first place — an impressive feat considering Tony was now too little to tell them himself. They had made another considerable dent in some chemicals that would possibly counteract the age effects... but testing them would take time; time that they didn’t really have today, anyway.  
Bruce squinted. “Kid, he’s a baby. You don’t have to call him Mr. Stark.”

Peter stopped. He thought about it. “The baby’s awake.” He amended, looking hopefully at Bruce. “Can I...?”

“Sure, sport. Don’t let him hear you calling him that, though.” Bruce grinned, shrugging him off.

*

“Hi Mr. Stark. This grilled cheese is really really good.” Peter said, kneeling in front of the baby as he chewed on a corner of his own sandwich and held out a triangular piece in front of Tony’s mouth.   
Tony looked at the triangle in Peter’s hand until he went cross-eyed and shook his head, scooting away on his bottom. He frowned, and tried his hardest to let out a, ‘no’, but all that came out was a “Nuhhh!” instead.   
Peter frowned. He leaned in closer and insisted, wiggling the triangle of toast and cheese at the baby. “C’mon. You can have soup.” He dipped the triangle into the bowl and offered it to Tony again. 

“Nuh.” Tony insisted. _Since when did he need the kid to feed him a grilled cheese? Hell, he had been eating grilled cheese sandwiches before the kid had even been thought of, never mind born. He was not letting his kid, the kid he was meant to mentor, **feed** him._

“He doesn’t want to be fed.” Pepper called from the kitchen where she was sponging away at her blouse, which had a few suspicious orange stains on it. “But he has to be, because otherwise he makes a mess. He’s too little to feed himself.” Peter had the feeling that this was more for Tony’s benefit than his own. He had turned away, and a frown was currently eating away at his features. At the same time, a blush crept up his neck.

Peter slowly put the sandwich back onto the plate. He looked at Pepper. She was busy. Or at least distracted enough. Good. He looked toward Tony and dropped his voice to a whisper. “Hey.”

Tony knew that tone of voice. That was Peter’s, ‘I’m about to be cheeky’ tone of voice. He turned to face the teenager once more.   
Peter pushed the soup bowl and sandwich toward Tony. “Go nuts.” he giggled. What Pepper didn’t know, wouldn’t hurt her. 

Tony smiled for what seemed like the first time in ages. He picked up a triangular slice of the sandwich in one chubby little hand, squeezing it tightly. For a moment Tony wondered why grown ups never squeezed their food like this, because it felt... neat. He raised his chubby, crumb-filled and cheesy fist to Peter and grinned a gummy sort of grin. 

“Cool, right?” Peter asked. “Put it in the soup.”

Tony stared at the soup bowl as if Peter had just told him to solve a quadratic equation that was written on the bottom. Slowly, he released his fist and the crumby-cheesy triangle landed into the bowl with a plop. Was that right? Tony... didn’t actually know if that was right. He looked up toward Peter again, eyes crinkling like he was waiting for the teenager to yell at him. Except he didn’t - so Tony relaxed.   
“Okay, now eat it.” Peter said.   
Tony stared at the sandwich floating in his soup for a long, long moment before plunging his hand into the (thankfully cool) bowl and yanking out the (now soggy) sandwich. He stuffed it into his mouth with a ‘mmmm’ noise of soft enjoyment; but given he had all the dexterity of an infant, this movement resulted in most of his sandwich and tomato soup getting splattered and smeared around his mouth. Still, what he had actually swallowed did taste nice... and so before Peter could squeeze in another word of encouragement Tony had pounced on the other three quarters of sandwich like a crazed puppy; dunking not one but both hands into the cheesy tomato-y soup in his bowl. By the time the entirety of the sandwich had disappeared, Tony was...

Tony was...

Pepper was right. Tony was a mess. 

It was really a sight to see. When Tony was a grown up he hated mess — hated seeing a speck of something on his super mega expensive suits, and winced any time Peter asked to eat something during their drive home in case he got sticky hands everywhere (even if Peter insisted he was a teenager now, not some sticky little toddler!)... but now? Now he was happily making sure he got crumbs and cheese and tomato soup into every nook and cranny of his face as was humanly possible. It was all over his hands. It was under his fingernails. It was speckled on his face and ears and splattered down the front of his once-crisp suit. Tony didn’t quite know what was so captivating about the whole thing, but... it just felt good. 

“Uh.. Miss Potts?” Peter laughed nervously, backing away from Tony as he tried to get little orange handprints all over everything. “Tony... uh... Tony needs a bath.”

*

“Oh, look at you.” Pepper cooed sympathetically, gently scrubbing soap suds into the curl of Tony’s ears in a vain attempt to wipe away the crusty soup. “Never mind. Lunch was good, huh?”  
It was bath time. Pepper had taken one look at the orange-handed child in their living room and declared there and then that it was most definitely bath time. Peter had not been allowed to help with this. Tony had refused. There was no way he was letting the kid help him with bath time. The only reason he had allowed Pepper to help him was because, hey, she had seen everything (Oh, and she could help him sit up properly so he didn’t, you know, drown.)  
Only a few nights ago they had shared a bath with a glass of wine or two. Now here he was, his fiancée soaping up his tummy and promising him a bottle—of milk—afterward. That particular fall from grace _hurt_.

Tony burbled dejectedly, kicking at the water. Pepper lifted him out of the bathtub and into a warm towel, holding him close. He melted into her, taking in her warmth and the smell of her perfume that always seemed to cling to her, and slowly began to calm down. When he was a grown up he had always liked the scent Pepper wore, but as a baby it seemed that bit more enchanting - like it hugged him, right around the middle. “Let’s get you dressed.” She said, and for once Tony didn’t mind so long as she kept hold of him. “Peter found you a nice new romper, like I asked. Much cosier than that stiff old suit.”   
Sure enough, there on the bed was a red patterned romper — made to look exactly like the Iron Man suit. It even had feet!  
 _“Where did he even find this?”_ Tony asked or rather babbled as he nudged the sleeper. 

“Yeah, it’s cute isn’t it?” Pepper grinned. “I’d say Peter makes a good personal shopper.”  
Tony decided to ignore the fact that Pepper wasn’t actually answering him. She patted him dry, put him into a fresh diaper (which was miraculously less embarrassing than the first time) and buttoned up the snaps of the romper shortly afterwards.

*

“Don’t get into trouble now.” Pepper told Tony, plopping him down in front of the blocks she had brought in specially. Bruce had told her that this was likely to be a ‘longer-than-one-day’ deal, and while she was stocking up on diapers earlier on she figured, hey, might as well entertain him somehow - and maybe (she prayed) the blocks would at least tap into his engineering streak. “Peter’s going to look after you and I’ll make you supper after I drop him home.”

Tony eyed his teenage babysitter grumpily as he was put down with the blocks. _“I thought he was meant to be helping Bruce,”_ he said as Pepper disappeared. He couldn’t help but feel like a bit of a circus animal on display, with the way everyone was acting toward him. Peter had turned into some sort of manic kids’ TV presenter, by the looks of things.

“Yeah!” Peter’s eyes lit up at all of Tony’s babbling and he giggled animatedly, crouching down with the blocks. Point proven. “These blocks are kinda cool, aren’t they? Hey, I’ll build with you, if you want.”

Tony sighed—was no one listening to him today?—and accepted his fate. _Blocks. Really, Pepper? Blocks. Since when had he ever given the slightest interest in **building blocks?** Building blocks with the alphabet printed on them, to add insult to injury. How old did Pepper think he was, exactly? If she thought he’d be distracted by blocks, she was sorely mistak—_

Peter could see that Tony wasn’t doing anything other than looking at the blocks. Maybe he needed a little bit of help? Even if he was still Mr. Stark, and he was still clever, he was just a baby now, so... maybe things were a little tough. Heck, he seemed to have forgotten how to feed himself earlier on. Settling in with his legs crossed, Peter began piling blocks messily on top of one another. It almost reached the point where he had forgotten Mr. Stark was even there because, hey, building blocks was just baby Lego, right? Still fun. As he pulled himself to his knees to put the last block on top of the precariously wobbling tower, tongue poking out with the utmost concentration, it was as though he suddenly remembered where he was and crashed down once more. “There, see? A tower. Avengers tower! Made outta building blocks.” He told the baby. “Now what?”

Tony, who had been captivated by Peter’s building of the tower until that point, finally ripped his gaze away. He looked at Peter. Then at the tower. Then at Peter, and at the tower once more. _Jeez. If that was meant to be the Avengers tower, kid needed his eyes checked._ But in the back of his mind there was a tiny voice, a voice getting harder and harder to ignore, a voice that pawed at him excitedly. _Push it, go on, push it over..._

Tony looked at Peter

and pushed the tower of blocks over with all of his might. The coloured blocks toppled around them - Peter pretended to yell and hide - and with that, Tony giggled before he could stop himself. He reached for the blocks again.

“More?” Peter grinned. “Ok!”

This routine went on for a short while; Peter building block towers, and Tony pushing them over while Peter ‘ran for cover’. This was, apparently, hysterically funny — bringing Tony into belly laughs time and time again until his little belly hurt from laughter and he had tumbled over onto his back, legs in the air, cooing babyish nonsense that even he wasn’t sure of. 

“Are you enjoying yourself?” Pepper asked, peering in from the kitchen. She beamed. 

Oh. Yeah. He wasn’t meant to be enjoying himself. Pulling himself to a shaky sitting position, Tony put on his best ‘unimpressed’ face. Keeping his eyes locked on Pepper, he pulled all of the blocks closer to him and set them out. Yeah. He’d show Pepper how much he was really enjoying himself. Yeah.

F U C K  
S H I T  
D I

“Oh Tony, that’s enough!” Pepper tutted, swiping his hands away from the blocks. “Play nicely.”

Peter waited, squirming on his bottom until Pepper had gone, before he spoke. “Mr. Stark,” he asked quietly - voice hushed as quiet as he could make it with only the tiniest bit of cheekiness melting in. “What’s the rudest word you know?”

Tony looked at Peter and thought for a long time.

D I C K  
H E A D

Peter wasn’t quite sure if Mr. Stark was just protecting him, or if he had forgotten all of the good swears now that he was a baby. Still.. “Am I allowed to say that one?”

Tony didn’t need to think this time. 

N O

*

It was when they were tidying away the blocks that Peter realised. And nearly kicked himself for not realising sooner. “Mr. Stark!” He gasped, watching the baby toddle with an armful of blocks. “I just realised something.”

Tony turned to face Peter. He was laughing. Tony didn’t like the look of it for some reason.

“You’re, like... _literally_ the Boss Baby right now. Heh..”

Tony looked puzzled. _“Uh yeah, kid. I’m going to pretend that whatever you just said was actually English and move on.”_ he babbled. Peter, ironically, had no idea what he was saying, but the puzzled look on his face remained, so the teenager could guess quite easily. 

“You mean you haven’t seen the Boss Baby?” Peter gasped, as though this was some sort of crime. He whisked Tony up under the armpits and held him close. “Oh, man, we gotta change that. We gotta change that, like, right now. See, there’s this film, and there’s also a Netflix adaptation, and...”

Tony let Peter trail off as he was carried toward the cinema room, educating him on whatever ‘me me’s’ were, for two hours of some kid’s film that he’d probably fall asleep half way through - and that was without factoring in that he was currently stuck being a baby who was close to bedtime. Still, it was the closest him and Peter had been for a while, so...

...so really, he didn’t really mind. 

Actually, no. He did mind. He minded being fed spoonfuls of luminous orange mush by his fiancée and nearly spitting up over her in return. 

The rest... the rest wasn’t too bad.

(Just don’t let Pepper know he said that.)

**Author's Note:**

> I hope you enjoyed. comment n kudos me if you did. you can say hello to the baby if you like, he’s right here. 
> 
> *twirls around with baby Tony in arms*
> 
> ...can one of you babysit so I can study?
> 
> ...anyone?
> 
> huh.
> 
> xx.


End file.
